One embodiment of the present invention relates to modems and more specifically to MEDLEY symbols in ADSL modems.
Pseudo-random bit sequence (hereinafter referred to as “PRBS”) generators or scramblers have various uses in ADSL modems that conform to ITU-T Recommendations G.992.1 and G.992.2, both of which are hereby incorporated herein by reference. It should be appreciated that the term PRBS generator as used herein to identify either a pure PRBS generator or a scrambler based on a PRBS generator. Specifically, two different PRBS generators define the MEDLEY signal used for upstream and downstream training. A different PRBS sequence defines the form of the REVERB signal used in training while user data are scrambled during SHOWTIME using still another different PRBS generator.
Such a plurality of uses of PRBS generators in ADSL training demonstrates a need for means in an ADSL modem to select one of a set of different PRBS generators appropriate to observations made during training or to parameters that may not be known in advance.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.